Effects of Deep-Brain Stimulation on Speech: Perceptual and Acoustic Data.

PURPOSE: This study examined speech changes induced by deep-brain stimulation (DBS) in speakers with Parkinson's disease (PD) using a set of auditory-perceptual and acoustic measures. METHOD: Speech recordings from nine speakers with PD and DBS were compared between DBS-On and DBS-Off conditions using auditory-perceptual and acoustic analyses. Auditory-perceptual ratings included voice quality, articulation precision, prosody, speech intelligibility, and listening effort obtained from 44 listeners. Acoustic measures were made for voicing proportion, second formant frequency slope, vowel dispersion, articulation rate, and range of fundamental frequency and intensity. RESULTS: No significant changes were found between DBS-On and DBS-Off for the five perceptual ratings. Four of six acoustic measures revealed significant differences between the two conditions. While articulation rate and acoustic vowel dispersion increased, voicing proportion and intensity range decreased from the DBS-Off to DBS-On condition. However, a visual examination of the data indicated that the statistical significance was mostly driven by a small number of participants, while the majority did not show a consistent pattern of such changes. CONCLUSIONS: Our data, in general, indicate no-to-minimal changes in speech production ensued from DBS stimulation. The findings are discussed with a focus on large interspeaker variability in PD in terms of their speech characteristics and the potential effects of DBS on speech.

Articulatory and Vocal Fold Movement Patterns During Loud Speech in Children With Cerebral Palsy.

PURPOSE: Speech motor control changes underlying louder speech are poorly understood in children with cerebral palsy (CP). The current study evaluates changes in the oral articulatory and laryngeal subsystems in children with CP and their typically developing (TD) peers during louder speech. METHOD: Nine children with CP and nine age- and sex-matched TD peers produced sentence repetitions in two conditions: (a) with their habitual rate and loudness and (b) with louder speech. Lip and jaw movements were recorded with optical motion capture. Acoustic recordings were obtained to evaluate vocal fold articulation. RESULTS: Children with CP had smaller jaw movements, larger lower lip movements, slower jaw speeds, faster lip speeds, reduced interarticulator coordination, reduced low-frequency spectral tilt, and lower cepstral peak prominences (CPP) in comparison to their TD peers. Both groups produced louder speech with larger lip and jaw movements, faster lip and jaw speeds, increased temporal coordination, reduced movement variability, reduced spectral tilt, and increased CPP. CONCLUSIONS: Children with CP differ from their TD peers in the speech motor control of both the oral articulatory and laryngeal subsystems. Both groups alter oral articulatory and vocal fold movements when cued to speak loudly, which may contribute to the increased intelligibility associated with louder speech. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24970302.

Proprioceptive Acuity Influences Speech Motor Control in Healthy Adult Talkers.

PURPOSE: Somatosensory feedback, including proprioception, is important for speech production. This study evaluates proprioceptive acuity of the tongue using a position-matching task and determining if proprioceptive acuity impacts speech motor control in healthy adult talkers. METHOD: Twenty-five young adults with no history of speech, language, or hearing disorders had their tongue movements recorded with an electromagnetic articulograph while completing a position-matching task. Participants were also asked to repeat two sentences that differed in the somatosensory feedback obtained. One sentence provided both tactile and proprioceptive feedback, whereas the other primarily provided proprioceptive feedback. RESULTS: Participants ranged in proprioceptive acuity as measured by the position-matching task. Talkers with smaller position-matching errors and, therefore, higher proprioceptive acuity had smaller movements and slower speeds for both sentences. Talkers with lower proprioceptive acuity had reduced speech movement stability for the sentence that primarily provides proprioceptive feedback. CONCLUSION: Proprioceptive acuity of the tongue can be evaluated using a position-matching task, and acuity is associated with more efficient speech movements and greater speech movement stability, particularly when producing utterances that provide less tactile feedback. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24293740.

The Effects of Deep Brain Stimulation on Speech Motor Control in People With Parkinson's Disease.

PURPOSE: Despite the overall benefits of deep brain stimulation (DBS) in Parkinson's disease (PD), its effects on speech production have been mixed when examined using auditory-perceptual and acoustic measures. This study investigated the effects of DBS on the lip and jaw kinematics during sentence production in individuals with dysarthria secondary to PD. METHOD: Twenty-seven participants from three groups were included in the study: (a) individuals with PD and without DBS (PD group), (b) individuals with PD and with DBS (PD-DBS group), and (c) neurologically healthy control speakers (HC group). Lip and jaw movements during speech were recorded using optical motion capture and analyzed for path distance, speed, duration, articulatory stability, and interarticulator coordination. RESULTS: The PD-DBS group showed (a) increased path distance compared with the PD and HC groups and (b) increased speed compared with the PD group but not the HC group. Both PD and PD-DBS groups exhibited lengthened sentence duration compared with the HC group. Articulatory stability was greater for the two PD groups, PD and PD-DBS, compared with the HC group. Spatial, but not temporal, coordination was lower for the PD group than for the other two groups. The only kinematic changes between the DBS on and off conditions within the PD-DBS group were increases in spatial coordination. CONCLUSIONS: These data suggest that DBS primarily affects the amplitude scaling of articulatory movements, but not the temporal scaling, in individuals with PD. The findings are discussed with respect to the DBS-induced neural changes and their effects on speech motor control in PD.

Use of Automated Kinematic Diadochokinesis Analysis to Identify Potential Indicators of Speech Motor Involvement in Children With Cerebral Palsy.

PURPOSE: This study examined multiple variables obtained from an automated measure of lip movement during a diadochokinesis (DDK) task to identify those with potential to detect mild speech motor involvement in school-age children diagnosed with cerebral palsy (CP). METHOD: Eight children with CP and high speech intelligibility and a matched group of eight children with typical development (TD) completed a DDK task while their lip and jaw movements were recorded. A custom MATLAB algorithm was used to automatically extract 23 kinematic measures of children's lip movements during production of the DDK sequences. Mann-Whitney U tests were used to compare groups on the kinematic measures, and receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of measures that significantly differed between groups. RESULTS: Five of the 23 kinematic variables differed significantly between the CP and TD groups. These were two measures of overall DDK performance (i.e., duration of the DDK sequence and number of cycles) and three spatial and temporal measures of lip movement. Duration of the DDK sequence and the mean displacement of the lips across cycles had the highest diagnostic accuracy, differentiating CP and TD groups with 88% sensitivity and 88% specificity. CONCLUSIONS: Automatically derived kinematic measures of DDK sequences differentiated children with CP and high intelligibility from typically developing children. Future research is needed to determine the clinical utility of these measures for detecting speech motor impairment.

Native Language and Second Language Convergence and Second Language Instruction Shape Speech-Language Performance in Adult Learners.

PURPOSE: We examined native language (L1) and second language (L2) convergence of underlying skills in adult L2 learners as well as the contribution of instructional L2 level on L2 attainment across speech motor, lexical, and narrative levels. METHOD: Thirty-four adult Spanish L2 learners who had completed at least 1 year of college Spanish participated in this preliminary study. Learners were tested at the speech motor, lexical, and narrative levels in their L1 (English) and L2 (Spanish). L1-L2 convergence was indexed by associative links between corresponding L1 and L2 skills. In regression analyses, the level of Spanish instruction at the time of the study was also considered as a predictor of L2 attainment across speech motor, lexical, and narrative levels. RESULTS: L1-L2 convergence was identified for some speech motor skills (distance, maximum speed) and for lexical skills but was limited for other speech motor skills (duration, spatiotemporal index) and for narrative measures. Furthermore, lexical and narrative measures, but not speech motor measures, showed improvements with Spanish (L2) instruction. CONCLUSIONS: L1-L2 convergence and instructional level are predictors of L2 performance in adult language learners. These factors play somewhat different roles across speech motor, lexical, and narrative levels, warranting further "all-system" research across processing and proficiency levels.

Voice Quality of Children With Cerebral Palsy.

Purpose Many children with cerebral palsy (CP) are described as having altered vocal quality. The current study utilizes psychoacoustic measures, namely, low-amplitude (H1*-H2*) and high-amplitude (H1*-A2*) spectral tilt and cepstral peak prominence (CPP), to identify the vocal fold articulation characteristics in this population. Method Eight children with CP and eight typically developing (TD) peers produced vowel singletons [i, ɑ, u] and a story retell task with the same vowels in the words "beets, Bobby, boots." H1*-H2*, H1*-A2*, and CPP were extracted from each vowel. Results were analyzed with mixed linear models to identify the effect of Group (CP, TD), Task (vowel singleton, story retell), and Vowel [i, ɑ, u] on the dependent variables. Results Children with CP have lower spectral tilt values (H1*-H2* and H1*-A2*) and lower CPP values than their TD peers. For both groups, vowel singletons were associated with lower CPP values as compared to story retell. Finally, the vowel [ɑ] was associated with higher spectral tilt and higher CPP values as compared to [i, u]. Conclusions Children with CP have more constricted and creaky vocal quality due to lower spectral tilt and greater noise. Unlike adults, children demonstrate poorer vocal fold articulation when producing vowel singletons as compared to story retell. Finally, low vowels like [ɑ] seem to be produced with less constriction and noise as compared to high vowels.

Spatial Characteristics of Jaw Movements During Chewing in Children with Cerebral Palsy: A Pilot Study.

This study compared jaw motion between children with cerebral palsy (CP) and their typically-developing (TD) peers during chewing. The jaw movements of 11 children with spastic CP (GMFCS levels II-V) all of whom were exclusively oral feeders with no reported clinical issues with feeding [mean age = 7.49 (2.30) years; 7 males, 4 females] and 11 age- and sex-matched TD peers [mean age = 7.54 (2.35) years] were recorded using optical motion capture. Participants chewed five trials of three different consistencies, including puree, mechanical soft, and solid. For each chewing sequence, the path distance (total amount of distance traveled by the jaw), average jaw speed, and working space (total 3-dimensional size of the jaw movements during chewing) were calculated. The CP group had greater path distances for mechanical soft and solids (p < 0.001) and larger working spaces (p < 0.001) than the TD group. Consistency differences were also found with path distances increasing for both groups with increased bolus consistency (p < 0.001). Puree was chewed most slowly for both groups (p = 0.05) and was associated with smaller working space than the other consistencies for both groups (p < 0.001). The TD group demonstrated slower speeds for mechanical soft as compared to solids (p = 0.05), a finding which was not observed in the CP group. The results suggest children with CP showed jaw movement differences during chewing despite being exclusive oral eaters with no reports of clinical feeding or deglutition disorders. Food consistency also influenced jaw movements in both children with CP and their TD peers.

Initial Observations of Lingual Movement Characteristics of Children With Cerebral Palsy.

Purpose: This preliminary study compared the speech motor control of the tongue and jaw between children with cerebral palsy (CP) and their typically developing (TD) peers. Method: Tongue tip and jaw movements of 4 boys with spastic CP and 4 age- and sex-matched TD peers were recorded using an electromagnetic articulograph during 10 repetitions of "Dad told stories today." The duration, path distance, average speed, and speech movement stability of the movements were calculated for each repetition. Results: The children with CP had longer durations than their TD peers. Children with CP had longer path distances and faster average speed as compared with their TD peers for both articulators. The TD group but not the CP group had longer path distances and faster average speeds for the tongue than the jaw. The CP group had reduced speech movement stability for the tongue as compared with their TD peers, but both groups had similar speech movement stability for the jaw. Conclusions: Children with CP had impaired speech motor control of the tongue and jaw as compared with their TD peers, and these speech motor control deficits were more pronounced in the tongue tip than the jaw.

Interarticulator coordination in children with and without cerebral palsy.

The current study investigates how interarticulator coordination changes across speaking tasks varying in articulatory and linguistic demands for children with CP and their typically-developing peers. Articulatory movements from 12 children with spastic CP (7M, 5F, 4-15 years of age) and 12 typically-developing age- and sex-matched peers were cross-correlated to determine the degree of spatial and temporal coupling between the upper lip and jaw, lower lip and jaw, and upper and lower lips. Spatial and temporal coupling were also correlated with intelligibility. Results indicated that children with CP have reduced spatial coupling between the upper and lower lips and reduced temporal coupling between all articulators as compared to their typically-developing peers. For all participants, sentences were produced with the greatest degree of interarticulator coordination when compared to the diadochokinetic and syllable repetition tasks. Measures of interarticulator coordination were correlated with intelligibility for the speakers with CP.

Proficiency and Linguistic Complexity Influence Speech Motor Control and Performance in Spanish Language Learners.

PURPOSE: Second-language (L2) production requires greater cognitive resources to inhibit the native language and to retrieve less robust lexical representations. The current investigation identifies how proficiency and linguistic complexity, specifically syntactic and lexical factors, influence speech motor control and performance. METHOD: Speech movements of 29 native English speakers with low or high proficiency in Spanish were recorded while producing simple and syntactically complex sentences in English and Spanish. Sentences were loaded with cognate (e.g., baby-bebé) or noncognate (e.g., dog-perro) words. Effects of proficiency, lexicality (cognate vs. noncognate), and syntactic complexity on maximum speed, range of movement, duration, and speech movement variability were examined. RESULTS: In general, speakers with lower L2 proficiency differed in their speech motor control and performance from speakers with higher L2 proficiency. Speakers with higher L2 proficiency generally had less speech movement variability, shorter phrase durations, greater maximum speeds, and greater ranges of movement. In addition, lexicality and syntactic complexity affected speech motor control and performance. CONCLUSIONS: L2 proficiency, lexicality, and syntactic complexity influence speech motor control and performance in adult L2 learners. Information about relationships between speech motor control, language proficiency, and cognitive-linguistic demands may be used to assess and treat bilingual clients and language learners.

Increases in cognitive and linguistic processing primarily account for increases in speaking rate with age.

Age-related increases of speaking rate are not fully understood, but have been attributed to gains in biologic factors and learned skills that support speech production. This study investigated developmental changes in speaking rate and articulatory kinematics of participants aged 4 (N = 7), 7 (N = 10), 10 (N = 9), 13 (N = 7), 16 (N = 9) years, and young adults (N = 11) in speaking tasks varying in task demands. Speaking rate increased with age, with decreases in pauses and articulator displacements but not increases in articulator movement speed. Movement speed did not appear to constrain the speaking. Rather, age-related increases in speaking rate are due to gains in cognitive and linguistic processing and speech motor control.

Kinematic Characteristics of Speaking Rate in Individuals with Cerebral Palsy: A Preliminary Study.

Many individuals with cerebral palsy (CP) have a slower speaking rate compared with their typically developing peers. Previous studies examining age-related changes in speaking rate in typical development suggest that (1) cognitive and linguistic processing increases account for most of these changes, and (2) changes to linguistic task demands affect the articulatory strategies used to produce the target stimuli (e.g., truncating movements for tasks with fewer linguistic demands). The purpose of this study was to determine the relations between linguistic and physiologic factors in individuals with CP to better understand how the pathophysiology of CP affects speech production in these individuals. Four participants with CP and 38 age-matched peers were asked to complete a diadochokinetic (DDK) task, a vowel-consonant-vowel syllable repetition task, and a sentence repetition task. Speaking rate for the tasks and lower lip maximum movement speed, range of movement, and duration of the closing and opening gestures common to each task were measured. In general, participants with CP have reduced speaking rates compared with their typically developing peers despite increased movement speeds. In both groups, linguistic task effects were observed; higher linguistic demands resulted in slower speaking rates and higher movement speeds. Range of movement was greater for participants with CP than their typically developing peers and may have contributed to the observed decreased speaking rates in individuals with CP.

Accuracy of perceptual and acoustic methods for the detection of inspiratory loci in spontaneous speech.

The present study investigates the accuracy of perceptually and acoustically determined inspiratory loci in spontaneous speech for the purpose of identifying breath groups. Sixteen participants were asked to talk about simple topics in daily life at a comfortable speaking rate and loudness while connected to a pneumotach and audio microphone. The locations of inspiratory loci were determined on the basis of the aerodynamic signal, which served as a reference for loci identified perceptually and acoustically. Signal detection theory was used to evaluate the accuracy of the methods. The results showed that the greatest accuracy in pause detection was achieved (1) perceptually, on the basis of agreement between at least two of three judges, and (2) acoustically, using a pause duration threshold of 300 ms. In general, the perceptually based method was more accurate than was the acoustically based method. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci for spontaneous speech should be weighed in selecting a method of breath group determination.

The co-emergence of cognition, language, and speech motor control in early development: a longitudinal correlation study.

UNLABELLED: Although the development of spoken language is dependent on the emergence of cognitive, language, and speech motor skills, knowledge about how these domains interact during the early stages of communication development is currently limited. This exploratory investigation examines the strength of associations between longitudinal changes in articulatory kinematics and development of skills in multiple domains thought to support early communication development. Twenty-four children were investigated every 3 months between the ages of 9 and 21 months. Movements of the upper lip, lower lip, and jaw were transduced using a three-dimensional motion capture system to obtain age-related changes in movement speed and range of movement. Standardized measures of cognition and language from the Battelle Developmental Inventory, 2nd edition and the MacArthur-Bates Communicative Development Inventory were also collected. Significant associations were identified between orofacial kinematic and the standardized measures of language and cognitive skills, even when age served as covariate. These findings provide preliminary evidence of interactions between cognition, language, and speech motor skills during early communication development. Further work is needed to identify and quantify causal relations among these co-emerging skills. LEARNING OUTCOMES: The reader will be able to: (1) describe how cognition, language, and speech motor control may interact during speech development, (2) describe the associations between speech kinematic characteristics and measures of cognition and language.

Accuracy of perceptually based and acoustically based inspiratory loci in reading.

Investigations of speech often involve the identification of inspiratory loci in continuous recordings of speech. The present study investigates the accuracy of perceptually determined and acoustically determined inspiratory loci. While wearing a circumferentially vented mask connected to a pneumotach, 16 participants read two passages. The perceptually determined and acoustically determined inspiratory loci were compared with the actual loci of inspiration, which were determined aerodynamically. The results showed that (1) agreement across all three judges was the most accurate of the approaches considered here for detecting inspiratory loci based on listening; (2) the most accurate pause duration threshold for detecting inspiratory loci was 250 msec; and (3) the perceptually based breath-group determination was more accurate than the acoustically based determination of pause duration. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci are not negligible and, therefore, need to be considered when researchers design experiments on breath groups in speech.

Lip movement exaggerations during infant-directed speech.

PURPOSE: Although a growing body of literature has identified the positive effects of visual speech on speech and language learning, oral movements of infant-directed speech (IDS) have rarely been studied. This investigation used 3-dimensional motion capture technology to describe how mothers modify their lip movements when talking to their infants. METHOD: Lip movements were recorded from 25 mothers as they spoke to their infants and other adults. Lip shapes were analyzed for differences across speaking conditions. The maximum fundamental frequency, duration, acoustic intensity, and first and second formant frequency of each vowel also were measured. RESULTS: Lip movements were significantly larger during IDS than during adult-directed speech, although the exaggerations were vowel specific. All of the vowels produced during IDS were characterized by an elevated vocal pitch and a slowed speaking rate when compared with vowels produced during adult-directed speech. CONCLUSION: The pattern of lip-shape exaggerations did not provide support for the hypothesis that mothers produce exemplar visual models of vowels during IDS. Future work is required to determine whether the observed increases in vertical lip aperture engender visual and acoustic enhancements that facilitate the early learning of speech.

Breath group analysis for reading and spontaneous speech in healthy adults.

AIMS: The breath group can serve as a functional unit to define temporal and fundamental frequency (f0) features in continuous speech. These features of the breath group are determined by the physiologic, linguistic, and cognitive demands of communication. Reading and spontaneous speech are two speaking tasks that vary in these demands and are commonly used to evaluate speech performance for research and clinical applications. The purpose of this study is to examine differences between reading and spontaneous speech in the temporal and f0 aspects of their breath groups. METHODS: Sixteen participants read two passages and answered six questions while wearing a circumferentially vented mask connected to a pneumotach. The aerodynamic signal was used to identify inspiratory locations. The audio signal was used to analyze task differences in breath group structure, including temporal and f0 components. RESULTS: The main findings were that spontaneous speech task exhibited significantly more grammatically inappropriate breath group locations and longer breath group duration than did the passage reading task. CONCLUSION: The task differences in the percentage of grammatically inadequate breath group locations and in breath group duration for healthy adult speakers partly explain the differences in cognitive-linguistic load between the passage reading and spontaneous speech.

Early speech motor development: Cognitive and linguistic considerations.

UNLABELLED: This longitudinal investigation examines developmental changes in orofacial movements occurring during the early stages of communication development. The goals were to identify developmental trends in early speech motor performance and to determine how these trends differ across orofacial behaviors thought to vary in cognitive and linguistic demands (i.e., silent spontaneous movements, babble, and first words). Movements of the lower lip and jaw were recorded using a three-dimensional motion capture system. Twenty-four infants were observed every 3 months, from 9 to 21 months of age. Jaw and lower lip speed, and lower lip range of movement increased with age. Silent spontaneous movements were consistently slower than words, whereas kinematic measures associated with babble did not differ from those associated with words. These findings suggest that speech movements may reflect linguistic and cognitive processing demands and that the continuity hypothesis between babbling and words may also be observed at the kinematic level. LEARNING OUTCOMES: Readers will be able to: (1) describe the potential role of cognition and language in early speech development, (2) describe kinematic changes in the orofacial system from 9 to 21 months of age, and (3) identify the differences in kinematic characteristics for silent spontaneous orofacial movements, babbles and words between 15 to 21 months of age.